<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container{
            width: 800px;
            height: 400px;
            border: 1px solid #ccc;

            /* 弹性盒子、弹性布局 */
            display: flex;

            /* 水平对齐 */
            /* justify-content: center; */
            /* justify-content: space-between; */
            /* justify-content: space-around; */
            justify-content: space-evenly;

            /* 垂直对齐 */
            /* align-items: center; */
            /* align-items: end; */
            align-items: stretch;
        }
        .d1{
            width: 200px;
            /* height: 100px; */
            background: red;
        }
        .d2{
            width: 200px;
            /* height: 100px; */
            background: blue;
        }
        .d3{
            width: 200px;
            /* height: 100px; */
            background: green;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="d1">div1</div>
        <div class="d2">div2</div>
        <div class="d3">div3</div>
    </div>
</body>
</html>